Hi-Lok Ratchets?

What are these things? I've seen ones that look like Protos, then others that look quite odd.

hi lok ratchets are for use in aviation. They have a hole so you can put an allen wrench down the middle to hold the inside of a fastener while you turn, it. that is how one guy explained it to me. someone else may be able to do it a little better.

This is correct, I have a couple of snap on, got them cheap, and the newer ones have a clip to hold the socket on as well, the older snap on I have you had to use a screw in the socket to hold it on, I just changed the gear out in the older ones, and kept the newer ones with the clip which works fine.

The good ones are gearless. If you can so much as twitch the handle, you can get a fastener loose with them. I have one at home like this.

Think of a hi-lok as a countersunk screw, but with no drive in the head. There's a female hex in the threaded end. You put the "nut" (hi-lok collar) on it, put your ratchet/socket on, then put an allen wrench through that hole into the end of the hi-lok, and tighten.

The collar has a ring cut into it, so the part the socket drives snaps off at a preset torque, leaving a perfectly round "nut" on the fastener.

Technically, if the hi-lok fits right, the allen wrench should never be needed in the first place, but that's another story...